Radiotelegraphy



Patented Nov. 17, 1925.

UNITED STATES PATENT OFFICE.

RALPH R. BEAL, OF PALO ALTO. CALIFORNIA, ASSIGN'OR, BY MESNE ASSIGNMENTS,

TO FEDERAL TELEGRAPH COMPANY, OF SAN FRANCISCO, CALIFORNIA, A COR- PORATION OF CALIFORNIA.

RADIOTELEGRAPHY.

Application filed January 5, 1920. Serial No. 349,474.

To all whom it may concern:

Be it known that I, RALPH R. BEAL, a*

citizen of the'United States, and a resident of Palo Alto, county of Santa Clara, and 6 State of California, have invented certain new and useful Improvements in Radiotelegraphy, of which the following is a specification. I v The invention relates to transmission systems and particularly to a means of signaling. 1

An object of the invention is to provide a single wave radio signaling system.

The invention possesses other advantageous features, some of which, with the foregoing, will "be set forth at length in the following description, where I shall outline in full, that form of the invention which I have selected for illustration in the drawings accompanying and forming part of the present specification. In said drawings, I have shown one specific form of my invention, but it is to be understood that I do i not limit myself to such form, since the invention, as expressed in the claims, may be embodied in a plurality of forms.

Referring to said drawings: p u Figure 1 is a diagrammatic representation of a radio telegraph transmission system embodying my invention. I

- Figure 2 is a diagrammatic representation of a modified form of control means.

Figure 3 is a diagrammatic representation of a portion of amodified form of the 36 system, 1

The system includes a suitable source of oscillations, preferably continuous oscillations, such as the are 2 which operates in a hydrogen atmosphere. The are generator 4 is grounded on one side, preferablythe negative, and is connected on the other side to the antenna 3,'throu'gh the variable inductance or antenna loading coil 4. Direct current is supplied'to the are by the generator 5 and the arc'is subjectedto,a'strongtransverse magnetic-field producedby the combined magnet and choke coils 6, which are preferably arranged in the lead 7 connected to the antenna side of the arc.

Shunted across the arc is a second oscillatory circuit containing an inductance 12 acteristics than the antenna circuit. -When an arc is shunted by two oscillatory circuits having different electrical characteristics, it may be made to oscillate upon one circuitor the other, the circuit chosen being the one having the more favorable electrical characteristics. By varying the electrical constants of one or both of the oscillatory circuits, one of the circuits is chosen, to the practmal neglect of the other,-that is, by thls means the arc may be made to oscillate on the antenna circuit with very little or and vice versa. In general the arc will prefer to oscillate on the circuit of least resistance, and consequently, as the resistances are varied, the arc will first oscillate on one circuit and then 011 the other. The constants of the two circuits are such that when the resistance of the shunt circuit is increased and the resistance of the antenna circuit is decreased, the arc will, oscillate on the antenna circuit and, conversely, when the reslstance of the shunt circuit 1s decreased and the resistance of the antenna circuit increased the arc will oscillate on the shunt circuit. Instead of introducing the resistances directly into the antenna and shunt circuits, I introduce into the system resistances which have the equivalent eflect of introducing the resistances into the circuit; I

shunting several turns of the inductance 12 of the shunt circuit is a circuit containing a resistance 14 and a key15l shunting one or more of the lower turns of the antenna inductance 4 is a circuit containing aresistance '16 and a .key 17. The keys 15 and 1'7 are preferably connected together either mechanically,as by a rod 18 of insulating' material to which a signaling key 19 is secured, or electrically, as shown in Figure 2, wherein the keys 15 and. 17 are operated by solenoids 21. and 22 in the circult of the signaling key 19. Depression of the signaling key opens the key 17 and closes the key 15, causing the arc to oscillate on the antenna circuit, and releasing the signaling key opens the key 15 and closes the key 1?. causing the arc to oscillate on the shunt circuit.

In the system of connections shown, the change in effective resistance of either circuit is accompanied by a change in the natural frequency of the circuit, which increases the reactance of the circuit afi'ected, so that the closing of the key on one circuit not only has the effect of adding resistance to the circuit, but also adds reactance to the circuit by detuning it. This is advantageous because it increases the electrical dissimilarity of the two circuits and aids in decreasing the possibility of leakage current in the circuit in which the electrical characteristics have been made unfavorable. The change in frequency is not essential to the operation of the system, but by increasing the reactance of the circuit in which no current is desired, the leakage current, which would usually result from the inphase potential it the radiating and shunt circuits were of the same frequency, is reduced.

In Figure 8, I have shown a modified form of system in which a single resistance 23 is arranged in a conductor 24:, which is common to both resistance circuits. Two movable contacts 25-26, suitably insulated from each other and movable simultaneously are moved by a key 27 to open or close one or the other of the resistance circuits, so that the resistance 23 may be connected across one or more turns of the antenna inductance 4 or the shunt circuit inductance 12. The system shown in Figure 3 is identical with that shown in Figure 1 with the exception that a common resistance is em ployed which is alternately included in the two resistance circuits.

When a resistance circuit is closed, a radio frequency current will flow through the resistance, causing an energy loss, so that the resistance has the equivalent effect of being inserted in the circuit to which the resistance circuit is connected. The current through the resistance is probably not only the current in the circuit to which the resistance circuit is connected, but also a certain amount of induced current, due to the transformer action of the inductance to which the resistance circuit is connected, which inductance becomes in eflect an autotranstormer. I prefer to make the value of the resistance in ohms substantially equal to the reactance in ohms at radio frequency of the turns of the inductance, which are shunted by the resistance in order to cause a maximum energy loss in the resistance.

resistor I claim:

l. In a radio telegraphy transmission system, a source oi oscillations, a radiating circuit containing inductance permanently connectel to said source, .a local oscillatory circuit containing inductance permanently connected around said source, a circuit shunting said radiating circuit inductance, a resistor in said shunt circuit, a circuit shunting said local circuit inductance, a in said latter shunt circuit and means for opening and closing the shunt circuits.

2. In a radio telegraphy transmission sys tem, a source of oscillations, a radiating circuit containing inductance connected to said source, a non-radiating oscillating circuit containing inductance connected around said source, a circuit shunting said radiating circuit inductance, a resistor in said shunt circuit, a circuit shunting said nonradiating circuit inductance, a resistor in said latter circuit and a key for opening and closing both resistance circuits.

3. The combination with an oscillatory work circuit, of an oscillatory absorbing circuit connected in shunt thereto, a controlling resistor in each of said circuits, a switching means operable to open-circuit one of said controlling resistors and to closecircuit the other of said controlling resistors and the reverse process.

4. In an electrical system, a normally oscillatory work circuit, means included therein adapted to render the same non-oscillatory, a normally oscillatory idling circuit including means adapted to render the same non-oscillatory, and a single means operable at will to remove said means from one or the other of said circuits.

5. In a system employing oscillatory currents the method of suppressing oscillations in a work circuit without interrupting the source which consists in inserting a resistance in the work circuit at substantially the.

same instant that a resistance is removed from an idling circuit.

6. In an are system for radio signaling the method of signaling with but a single wave without extinguishing the are which consists in starting and stopping the flow of current in the antenna circuit to make signals by removing a resistance from the antenna circuit at substantially the same instant that a resistance is inserted in the idling circuit, and replacing the resistance in the antenna circuit at substantially the same instant that the resistance is removed from the idling circuit.

In testimony whereof, I have hereunto set my hand at Palo' Alto, California, this 29th day of December, 1919.

RALPH R. REAL. 

